2007 Yamaha YZ450F
General Specifications
| Model | Yamaha YZ450F |
| Year | 2007 |
| Category | Motocross |
| Engine Type | Liquid-cooled, 4-stroke, DOHC, 5-valve single-cylinder |
| Weight | Approximately 99.7 kg dry |
Engine
| Displacement | 449 cc |
| Bore x Stroke | 95.0 x 63.4 mm |
| Compression Ratio | 12.3:1 |
| Fuel System | Keihin FCR-MX39 flat-slide carburettor with throttle position sensor | Replacement Options |
| Ignition | CDI magneto |
| Spark Plug | NGK CR8E |
| Spark Plug Gap | 0.7-0.8 mm (0.028-0.031 in) |
| Cooling System | Liquid cooled |
| Starting System | Kick starter with automatic decompression and hot-start system |
Transmission
| Transmission | 5-speed constant-mesh |
| Clutch | Wet multi-plate |
| Final Drive | Chain, 13-tooth front / 49-tooth rear sprocket |
Dimensions
| Overall Length | 2,192 mm |
| Overall Width | 825 mm |
| Overall Height | 1,302 mm |
| Wheelbase | 1,495 mm |
| Ground Clearance | 370 mm |
| Seat Height | 986 mm |
| Fuel Capacity | 7.0 L |
Chassis
Suspension
| Front Suspension | 48 mm KYB inverted Speed Sensitive System twin-chamber fork, adjustable compression and rebound damping | Fork Oil Levels |
| Front Suspension Travel | 300 mm (11.8 in) |
| Rear Suspension | Link-type Monocross with KYB gas/oil shock, titanium spring, adjustable preload, high-/low-speed compression and rebound damping |
| Rear Suspension Travel | 315 mm (12.4 in) rear wheel travel |
| Fork Oil | Yamaha Suspension Oil S1; twin-chamber KYB fork with separate damper and outer-chamber oil. Standard outer-chamber quantity approximately 340 cc per fork; use the model-specific bleeding and filling procedure when servicing. |
Brakes & Wheels
| Front Brake | Hydraulic single disc, 250 mm |
| Rear Brake | Hydraulic single disc, 245 mm |
| Front Wheel Size | 21 x 1.60 in aluminium spoked wheel |
| Rear Wheel Size | 19 x 2.15 in aluminium spoked wheel |
Service Data
| Fuel Type | Premium unleaded petrol, minimum 95 RON |
| Premix Information | Not applicable - 4-stroke engine |
| Gearbox Oil | Engine and transmission share the same dry-sump engine oil supply; approximately 0.95 L periodic oil change, 1.0 L with oil filter replacement and 1.2 L total capacity. API SG or higher non-friction-modified 4-stroke motorcycle oil. |
| Air Filter | Wet-type foam element |
| Service Notes | Dry-sump lubrication. Maintain frequent oil and filter changes, check valve clearance regularly, keep the foam air filter clean and correctly oiled, and maintain correct FCR-MX39 jetting, accelerator-pump and hot-start operation. The 2007 model retained the aluminium frame and five-speed transmission introduced in 2006 while receiving detail engine, chassis and suspension refinements. |
2007 Yamaha YZ450F: Refining the Aluminium-Frame YZ450F
The 2007 Yamaha YZ450F was an evolutionary update rather than a new generation. Yamaha had completely redesigned the machine for 2006 with an aluminium frame, five-speed gearbox and KYB Speed Sensitive System suspension, so the following year concentrated on refining that already successful package.
The 449 cc liquid-cooled five-valve engine retained its 95.0 x 63.4 mm bore and stroke and 12.3:1 compression ratio. Fuel continued to be delivered through a Keihin FCR-MX39 flat-slide carburettor, with Yamaha revising settings to improve throttle response and power delivery. Owners maintaining the original carburettor can compare replacement and tuning options through the MXOwners carburettor reference.
The aluminium semi-double-cradle frame remained essentially the same concept introduced the previous year, while suspension settings were revised to improve balance and control. The 48 mm KYB Speed Sensitive System fork provided 300 mm of travel, and the linkage-operated Monocross rear suspension offered approximately 315 mm. Fork servicing information can be checked through the MXOwners fork oil reference.
The five-speed transmission, automatic decompression system and shared dry-sump engine and transmission lubrication were also retained. Regular oil changes, valve-clearance inspection and careful air-filter maintenance remain important on these high-output competition engines.
For owners today, the 2007 YZ450F is a well-developed early aluminium-frame model that combines strong carburetted five-valve power with Yamaha's established KYB suspension package. Model-specific parts can be checked through the MXOwners Parts Finder, while replacement tyre sizing can be compared using the MXOwners Tyre Size Guide.
